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      <title>Zookeeper如何处理节点间的数据同步 - 交互式测验</title>
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    </head>
    <body>
      <div class="main-wrapper">
          <div class="quiz-container">
            <div class="quiz-header">
              <h1>Zookeeper如何处理节点间的数据同步 - 交互式测验</h1>
              <p>检验你对文档内容的理解程度</p>
            </div>
            <div id="quiz-content">
                <div class="quiz-body">
                    <div class="progress-bar">
                        <div id="progress-indicator"></div>
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                    <div id="question-container">
                      <p id="question-text"></p>
                      <ul class="options-list" id="options-list"></ul>
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                    <div id="result-container"></div>
                    <div id="hint-container" class="hint-container"></div>
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                <div class="quiz-footer" id="quiz-footer">
                  <button id="prev-btn" class="nav-btn">上一题</button>
                  <button id="hint-btn" class="nav-btn" style="background-color: #ffc107; color: #333; box-shadow: 0 4px 12px rgba(255,193,7,0.3);">提示</button>
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                </div>
            </div>
          </div>
      </div>

      <script>
        const quizData = [
  {
    "question": "在 Zookeeper 集群中，一个写操作（例如创建或更新节点）在什么条件下才被最终确认为成功？",
    "options": [
      "当 Leader 节点将变更写入其本地事务日志后。",
      "当 Leader 节点收到集群中所有 Follower 节点的确认后。",
      "当 Leader 节点收到集群中大多数节点的确认后。",
      "当客户端的写请求被 Leader 节点接收时。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "Zookeeper 采用的是基于“大多数”确认的原则来保证数据的一致性和写操作的成功。Leader 节点在将变更广播给所有 Follower 后，并不需要等待所有节点都响应，只需要获得包括自己在内的超过半数节点的确认，就可以认为该操作已成功提交，并可以响应客户端。这种机制在保证数据一致性的同时，也提高了系统的容错性和可用性。",
    "source": "文档中「节点间的数据同步机制」下的「变更确认」部分",
    "hint": "思考一下，为了在部分节点失效时系统仍能工作，Zookeeper 是需要“全部”节点还是“大部分”节点同意？"
  },
  {
    "question": "根据文档，Zookeeper 的 Leader 节点在处理数据同步时扮演了什么核心角色？",
    "options": [
      "所有写操作都必须经过 Leader 节点处理和分发。",
      "Leader 节点只负责选举，不处理数据读写。",
      "Leader 节点和 Follower 节点都可以独立处理写操作。",
      "Leader 节点仅负责记录事务日志，由 Follower 节点执行写操作。"
    ],
    "correctAnswerIndex": 0,
    "explanation": "文档明确指出，Zookeeper 集群采用 Leader-Follower 模式。为了保证数据操作的顺序性和一致性，所有的写操作请求都必须由 Leader 节点统一处理。Leader 节点接收到写请求后，会先在本地执行并记录日志，然后通过原子广播协议将变更同步给所有的 Follower 节点。",
    "source": "文档中「节点间的数据同步机制」下的「Leader 和 Follower 角色」部分",
    "hint": "在 Zookeeper 的架构中，数据变更的“中央协调者”是哪个角色？"
  },
  {
    "question": "Zookeeper 的事务日志（Transaction Log）最主要的作用是什么？",
    "options": [
      "用于在节点重启或故障恢复时重建其数据状态。",
      "作为数据快照的替代品，用于长期数据备份。",
      "实时监控客户端的读写请求，用于性能分析。",
      "在 Leader 选举期间，用于节点之间进行投票。"
    ],
    "correctAnswerIndex": 0,
    "explanation": "事务日志是 Zookeeper 持久化机制的关键部分。它按顺序记录了所有对数据状态产生影响的写操作。当一个节点因为故障重启时，它可以根据本地的快照和事务日志，“重放”在快照之后发生的所有写操作，从而恢复到与集群一致的最新状态。",
    "source": "文档中「节点间的数据同步机制」下的「Zookeeper 的事务日志」部分",
    "hint": "当一个节点需要“回忆”起在它宕机期间发生的所有数据变更时，它会查阅什么记录？"
  },
  {
    "question": "当 Zookeeper 集群中现有的 Leader 节点发生故障时，集群会如何应对？",
    "options": [
      "集群会暂停所有服务，直到故障的 Leader 节点被手动恢复。",
      "集群会立即从 Follower 节点中选举出一个新的 Leader。",
      "所有 Follower 节点都会转变为可读写状态，共同分担 Leader 的工作。",
      "客户端会自动连接到数据最旧的节点，并将其指定为新 Leader。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "Zookeeper 具有高可用性，其核心机制之一就是自动的 Leader 选举。当集群通过心跳等健康检查机制发现 Leader 节点失效或失联时，剩余的 Follower 节点会立即进入选举流程，选出一个拥有最新数据的节点成为新的 Leader，从而快速恢复服务，继续处理客户端请求。",
    "source": "文档中「节点数据不一致时的处理」下的「选举机制」部分",
    "hint": "为了保证服务的高可用性，当“首领”倒下后，集群内部会自动发生什么来维持运转？"
  },
  {
    "question": "除了事务日志，Zookeeper 还使用哪种机制来提高节点故障恢复的速度和效率？",
    "options": [
      "数据快照 (Snapshot)",
      "Watch 机制 (Watcher)",
      "版本号 (Version Number)",
      "心跳机制 (Heartbeat)"
    ],
    "correctAnswerIndex": 0,
    "explanation": "如果仅依赖事务日志进行恢复，当日志文件非常大时，恢复过程会非常耗时。因此，Zookeeper 会定期将内存中的完整数据镜像以快照的形式持久化到磁盘。当节点重启时，它可以先加载最近的快照，然后只需应用该快照之后产生的事务日志即可，大大缩短了恢复时间。",
    "source": "文档中「节点数据不一致时的处理」下的「快照恢复」部分",
    "hint": "如果事务日志是一本详细的流水账，那么哪个机制相当于定期制作一张完整的“财务报表”来加速核对？"
  },
  {
    "question": "Zookeeper 使用什么协议来确保 Leader 的写操作变更能够被可靠且有序地广播到所有 Follower 节点？",
    "options": [
      "两阶段提交协议 (2PC)",
      "心跳协议 (Heartbeat Protocol)",
      "原子广播协议 (Atomic Broadcast Protocol)",
      "HTTP/2 协议"
    ],
    "correctAnswerIndex": 2,
    "explanation": "文档中明确提到，Zookeeper 使用原子广播协议来确保所有节点的数据同步。该协议保证了 Leader 发出的消息（数据变更）不仅会被所有 Follower 接收，而且所有 Follower 接收和处理这些消息的顺序也是完全一致的，这是实现强一致性模型的关键。",
    "source": "文档中「节点间的数据同步机制」下的「原子广播协议（Atomic Broadcast Protocol）」部分",
    "hint": "文档中提到了一个专有名词，用于描述一种能确保消息被所有节点按相同顺序接收的广播方式。"
  },
  {
    "question": "Zookeeper 节点中的版本号和序列号主要用于解决什么问题？",
    "options": [
      "限制客户端的连接数量。",
      "检测数据版本是否一致，并解决潜在的数据冲突。",
      "在 Leader 选举中作为节点的唯一标识。",
      "评估集群的整体性能负载。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "每个数据节点（ZNode）都带有一个版本号。当客户端尝试更新一个节点时，可以提供其期望的版本号。如果服务器上该节点的当前版本号与客户端提供的不匹配，更新操作就会失败。这是一种乐观锁机制，可以有效防止因并发修改导致的数据覆盖或不一致问题，从而解决数据冲突。",
    "source": "文档中「节点数据不一致时的处理」下的「版本号和序列号」部分",
    "hint": "这个机制类似于乐观锁，用于确保你正在修改的数据没有在你读取之后被其他人更改过。"
  }
];
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        let score = 0;
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            nextBtn.style.display = 'block';
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            html += `<div class="source-text">来源: ${questionData.source}</div>`;
            
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                // 如果选错了，高亮错误选项
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            document.getElementById('quiz-footer').style.display = 'none';

            const correctCount = score;
            const totalQuestions = quizData.length;
            const answeredCount = userAnswers.filter(a => a !== null).length;
            const wrongCount = answeredCount - correctCount;
            const skippedCount = totalQuestions - answeredCount;
            const accuracy = totalQuestions > 0 ? Math.round((correctCount / totalQuestions) * 100) : 0;
            const errorRate = totalQuestions > 0 ? Math.round((wrongCount / totalQuestions) * 100) : 0;

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                '<h2>答题报告</h2>' +
                '<div class="score-summary">' +
                '<div class="score-card">' +
                '<h3>得分</h3>' +
                '<p>' + correctCount + ' / ' + totalQuestions + '</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>正确率</h3>' +
                '<p>' + accuracy + '%</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>错误率</h3>' +
                '<p>' + errorRate + '%</p>' +
                '</div>' +
                '<div class="score-card score-details">' +
                '<table>' +
                '<tr><td>正确</td><td>' + correctCount + '</td></tr>' +
                '<tr><td>错误</td><td>' + wrongCount + '</td></tr>' +
                '<tr><td>未答</td><td>' + skippedCount + '</td></tr>' +
                '</table>' +
                '</div>' +
                '</div>' +
                '<div class="report-actions">' +
                '<button id="review-btn">回顾测验</button>' +
                '<button class="primary" onclick="location.reload()">再试一次</button>' +
                '</div>' +
                '</div>';

            let reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }
            quizContentEl.insertAdjacentHTML('beforeend', finalScoreHtml);
            document.getElementById('review-btn').addEventListener('click', reviewQuiz);
        }

        function reviewQuiz() {
            const reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }

            document.querySelector('.quiz-body').style.display = 'block';
            document.getElementById('quiz-footer').style.display = 'flex';
            
            currentQuestionIndex = 0;
            loadQuestion();
            updateNavigationButtons(); // Ensure nav buttons are correctly displayed
        }

        // Event Delegation for options
        optionsListEl.addEventListener('click', (event) => {
            if (event.target && event.target.matches('li.option-item')) {
                // Check if the question has already been answered
                if (userAnswers[currentQuestionIndex] === null) {
                    const selectedIndex = parseInt(event.target.dataset.index, 10);
                    selectOption(selectedIndex);
                }
            }
        });

        prevBtn.addEventListener('click', goToPreviousQuestion);
        nextBtn.addEventListener('click', goToNextQuestion);
        hintBtn.addEventListener('click', showHint);
        
        // 初始加载
        loadQuestion();
      </script>
    </body>
    </html>
  